Jacks Magic JMAFTER16 11 pt Container After Shock™ Chlorine Reducer. After Shock™ Chlorine Reducer is a chlorine reducer that is primarily used with Stain Solution #1, "The Iron, Cobalt and Spot Etching Stuff" to reduce the chlorine to below 1ppm. After Shock™ can also be used to quickly lower chlorine levels after shocking great for commercial pools.